Method and apparatus for extinguishing fires



Jan. 21, 1947. v wlLLlAMSON 2,414,683

METHOD AND APPARATUS FOR EXTINGUISHING FIRES Filed Nov. 18, 1944 s Sheets-Sheet '1 gwuwtom 1947- H. v. WILLIAMSON 2,414,683

METHOD AND APPARATUS FOR EXTINGUISHING FIRES Filed Nov. 18, 1944 3 Sheets-Sheet 2 SON 2,414,683

Jan. 21, 1947.

imam kw Patented Jan. 21, 1947 METHOD AND APPARATUS FOR EXTINGUISHING FIRES Hilding V. Williamson, Chicago, 111., assignor, by mesne assignments, to Cardox Corporation, Chicago, Ill., a corporation of Illinois Application November 18, 1944, Serial No. 564,097

8 Claims.

This invention relates generally to a method of and apparatus for extinguishing fires, and deals more specifically with the extinguishment of fires that are consuming flammable fluids.

Patent No. 2,352,379, issued to Eric Geertz, on June 27, 1944, discloses and broadly claims a mobile fire fighting unit which is particularly adapted for use in extinguishing airplane crash fires and in enabling trapped occupants of wrecked planes to be rescued.

In effecting the extinguishme'nt of a fire resulting from the crash landing of an airplane, the mobile unit of the above patent must be driven to a location in close proximity to the fuselage of the plane to enable the extinguishing materials to be properly applied to all involved portions of the wreckage. The fire, which is caused by the ignition of aviation gasoline that has been released from its regular storage spaces, always envelops the fuselage of the plane and frequently the entire wing structures are involved. For that reason, the mobile unit of the above noted patent is provided with discharge devices which are particularly adapted for applying the extinguishing materials to both the fuselage and the wing structures of a plane.

It was apparent from the start that spilled gasoline would produce a ground fire under elevated portions of the wrecked plane structure and over the immediately adjacent area. Hose lines were provided on the mobile unit for manual manipulation by the fire fighting crew to enable this type of fire to be extinguished. It soon was discovered that the intensity of the fire enveloping the fuselage of the plane was so great that the firemen handling the hose lines could not always successfully combat the ground fire burning close to the fuselage. Consequently, a ground-sweep discharge device, of the type disclosed and broadly claimed in Patent No. 2,357,040, issued to myself on August 29, 1944, was mounted on the front of the mobile unit and employed to extinguish this troublesome portion of the ground fire. This ground-sweep discharge device, also, was found to be very useful in extinguishing the ground fire in advance of the mobile unit to provide a path for the unit to move into the desired fire fighting position relative to the crashed plane.

One of th first extinguishments of an actual airplane crash fire with this type of mobile unit disclosed a fire condition which could not be dealt with properly with the discharge apparatus the units were equipped with at that time. This particular crash fire involved a plane carrying several hundred gallons of aviation gasoline. The impact was so severe that gasoline was thrown over a substantial area surrounding the wreckage. This spilled gasoline was ignited and the resulting ground fire covered all approaches to the plane for a substantial distance. The ground-sweep discharge device of the mobile unit that went into action very effectively created a path through this ground fire for the unit to move up to the plane. However, extinguishment of the fire involving the plane was hardly started before the crew manning the unit discovered that it was entirely surrounded by ground fire. The gasoline covering the path over which the mobile unit had traveled had reignited as a result of a flash-back from the remainder of the ground fire which .had not been extinguished. This extremely hazardcus fire condition was encountered on several other occasions before thepresent solution for the problem was conceived.

In analyzing this fire condition, it was very apparent that the carbon dioxide discharge provided by the ground-sweep device functioned quickly enough to effect extinguishment of the ground fire in advance of the moving mobile unit. However, after the unit had passed over a given area, the carbon dioxide was quickly dissipated and the unconsumed gasoline lying on said area would be reignited from any remaining fire area that was so positioned as to propagate flame thereto.

A foam blanket is recognized as being the most effective medium that can be employed for preventing reignition of a body of flammable fluid. However, foam is a very slow acting extinguishing medium. That is to say, the foam must be discharged onto the surface of the burning liquid for a substantial length of time before the characteristic blanket starts to form. This is due to the fact that the heat of the fire breaks down, or destroys, the bubble formation of the foam until the cooling effect of the water, which constitutes a large percentage of the foam, effects a substantial lowering of the temperatureof the combustible vapor, or fuel, that is rising from the body of flammable liquid. After the temperature of the combustible fuel has been lowered to a value which will no longer destroy the bubble formation of the foam, the smothering foam blanket will start to form over the surface of the body of liquid. This blanket usually is formed by the building up of the foam at the point of direct application and the spreading out of the foam under its own weight.

It was. apparent that foam could not be discharged from the ground-sweep devices of the mobile units, in place of the carbon dioxide then being used, and effect extinguishment of the ground fire in advance of the moving units if said units were to travel at faster than a snails pace. It is very obvious that every second counts in fighting a crashed airplane fire if one hopes to rescue trapped occupants of the plane and to hold to a minimum property damage.

Experiments finally led to the discovery that a combined discharge of carbon dioxide and foam could be produced which would actually function to effect extinguishment of the ground fire more quickly than when carbon dioxide was used by itself and a foam blanket of sufficient thickness to prevent reignition of the unconsumed gasoline could be built up and spread over a path of desired width while a mobile unit was traveling at an entirely satisfactory rate of speed.

It is the primary object of this invention to provide a method of and apparatus for quickly extinguishing ground fires, or the like, involving spilled or flammable liquids and for preventing reignition of the unconsumed liquids after such extinguishment.

Although the method and apparatus embodying this invention were developed for and are extremely effective in extinguishing ground fires involving spilled or flammable liquids, it readily will be appreciated that the disclosed discharge apparatus, and the method it performs of producing a combined discharge of carbon dioxide and foam, are equally well adapted for extinguishing fires involving bodies of flammable liquids that are confined in tanks, pools, ponds, or the like, an for preventing reignition thereof.

Therefore, it is a further primary object-of this invention to provide a method of and ap- 'paratus for quickly extinguishing fires involving confined bodies of flammable liquids, and for preventing reignition of said liquids after such extinguishment,

Still another important object of the invention is to provide a method of and apparatus for effecting a discharge of carbon dioxide and foam in which the snow and vapor components of the carbon dioxide are segregated from each other and are formed into a composite stream which will possess highly effective range and penetrating characteristics as well as a large field of application, or area of coverage, and in which the foam is discharged into the carbon dioxide stream in such a manner as to utilize the range and penetrating characteristics, as well as the large field of application or area of coverage, of the carbon dioxide stream to provide a corresponding uniform and continuous spread of the blanket formin foam over the surface covered by the carbon dioxide discharge.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts throughout the same,

Figure l is a side elevational view of the front portion of a mobile fire fighting unit with the fire extinguishing apparatus embodying this invention properly applied thereto,

Figure 2 is a plan view of the fire fighting apparatus disclosed in Fig. 1 as being applied to said mobile unit,

Figure 3 is a front elevational view of the said fire fighting apparatus,

Figure 4 is a vertical sectional view taken on line 43 of Fig. 3,

Figure 5 is a diagrammatic View which discloses in plan the type of discharge and area of coverage of the composite carbon dioxide and foam extinguisher produced by the apparatus embodying this invention, and

Figure 6 is a diagrammatic view disclosing the type of discharge in side elevation.

In the drawings, wherein for the purpose of illustration is shown the preferred embodiment of this invention, Fig. l. discloses the front end portion of a mobile fire fighting unit which is.

designated in its entirety by the reference character i. This mobile unit may take the form of the airplane crash truck of the above noted Eric Geertz patent, or the unit 7 may take the form of any other type of mobile fire fighting apparatus which is intended for use in combatting ground fires, or other fire hazards involving com.- bustible materials that are spread over surfaces that can be approached by the mobile unit 1. Fig. 1, also, discloses the fire. fighting apparatus embodying this invention as being properly applied to the front of the mobile unit 1 so as to project forwardly thereof. This apparatus is designated in its entirety by the reference character 8. It functions to produce a composite or combined discharge of carbon dioxide snow and vapor with foam uniformly distributed therethrough.

Although the fire fighting apparatus 8 is specifically disclosed as being applied to a mobile fire fighting unit, it readily will be understood by those skilled in the art that this extinguishing apparatus just as readily can be mounted on a suitable fixed or stationary support and arranged for applying its extinguishing material to a fire hazard of fixed location. For example, this fire fiighting apparatus 3 may be mounted on a fixed support that is located at the margin of a body of flammable fluid, or other combustible material, that is confined in a tank, a pool, a pond, or the like.

The fire fighting apparatus 8 must necessarily be supplied with the proper amounts of liquid carbon dioxide and mechanical air or chemical foam. No attempt has been made to provide a disclosure of suitable sources of supply for these extinguishers. However, reference may be made to the c-opending application filed in the name of Charles A. Getz, on August 30, 1944, bearing Serial No. 551,869, for disclosure of suitable sources of supply of carbon dioxide and mechanical air foam or chemical foam.

Figs. 2, 3 and 4 disclose in detail the fire fighting apparatus 8 as including a carbon dioxide discharge nozzle portion 9 and a plurality of foam generating and discharging devices or guns Hi. The carbon dioxide discharge portion or nozzle 9 is of the same general construction as that disclosed in my aforementioned Patent No. 2,357,040. This nozzle includes a pipe II which is employed for supplying the liquid carbon dioxide to the nozzle. This pipe l! is disclosed in Figs. 1 and 2 as being suitably coupled to a pipe line 52 that extends to a suitable source of supply of liquid carbon dioxide. This source of supply may consist of either a single, insulated storage tank in which the liquid carbon dioxide is maintained at a constant, low temperature, and its corresponding lo-w vapor pressure, or it may consist of a bank of cylinders in which the liquid carbon dioxide is stored at the ambient temperature. a

The forward end Ila of the pipe II is angularly arranged with respect to the remainder of posite ends and each pipe is provided with a 1011- gitudinally arranged series of discharge apertures or orifices M. Fig. 4 discloses these apertures or orifices as facing in a general rearward direction, rather than a forward direction, and it is to be understood that the apertures or orifices may be spaced at any desired or suitable distance fro-m each other.

Each one of these apertured discharge pipes 13 is arranged within a merging and segregating chamber i5. These chambers are arranged in parallelism with each other and each one is provided with a curvedrear wall It that is joined to the side, parallel walls ll. Each one of these chambers is entirely open at its front, or at the portion opposite its curved rear wall It, and both ends of each chamber are closed by the end Walls 18.

Fig. 4 discloses the discharge pipes I3 as being welded at E9 to the outer side walls ll of their respective chambers 45. The remaining, or inner, side walls ll of the parallel chambers bear against each other and they may be welded, or otherwise suitably connected, as at [9a. A reinforcing and bracing plate it is disclosed in Figs. 2, 3 and 4 as being welded, or otherwise suitably connected, to the outer surfaces of the curved inner walls 16 of the chambers for further interconnecting these two chambers.

By inspecting Fig. 4, it will be seen that the longitudinal series of discharge apertures or orifices I4 of each discharge pipe I3 point or face in the general direction of the zone or region where its associated rear, curved chamber wall l6 merges "with the outer side chamber wall IT. The importance of this direction of discharge will be apparent as the description proceeds.

The mode of operation of this carbon dioxide discharge nozzle now will be described. Liquid carbon dioxide of any desired temperature, and corresponding vapor pressure, will flow under its own vapor pressure through the pipes l2, II and Ila and the branches l2a to the parallel discharge pipes l3. The liquid carbon dioxide in these discharge pipes will be released to the interiors of the chambers l5 through the constricted orifices or apertures l4. Due to the sudden drop in pressure which occurs as a result of releasing the liquid carbon dioxide in this manner, the liquid is converted to a mixture of snow particles and vapor. Each aperture or orifice M will provide a separate jet or stream of this carbon dioxide mixture. These jets or streams will partake of straight-line motion until their paths are obstructed by the inner surfaces of the chamber walls. The curved formation of each chamber rear wall It will cause the flowing mixtures of carbon dioxide snow and vapor to be deflected so that the said normal straight-line motion will be converted to a curvilinear motion. Inaddition to partaking of this curvilinear motion, the snow and vapor mixtures of the several streams or jets released into each one of the chambers 15 will be permitted to spread longitudinally of the chamber with the result that the various mixtures will merge to form a continuous mass equal in length to each chamber Hi.

It is a well recognized law or principle of physics that any object or material which is set in motion will travel in a straight line unless some force is applied thereto which will deflect it from such a path of movement. Additionally, the force required to deflect the object or material from its straight line motion depends on the velocity and the mass or density of the object or material being deflected.

The curved surfaces of the rear chamber walls I6 have been described above as functioning to accomplish a change in the direction of motion of the released carbon dioxide snow and. vapor. These curved chamber walls, therefore, provide the opposing force referred to in the above noted principle of physics. As the carbon dioxide snow of the mixture is many times more dense than the carbon dioxide vapor, and as the velocity of both of these components is the same, the snow offers more resistance to the deflecting force provided by the rear, curved chamber walls. The snow, therefore, will force its way to the outer side of the curvilinear path of flow of the material with the result that it will displace the vapor, fOI'ciIig it to seek a path of flow away from the surface of the chamber wall. The difference in density of the snow, as compared to the vapor, therefore, brings about a segregation of these two components. That is to say, the snow will form a flowing layer in contact with the inner Wall surface of each chamber while the vapor forms a superimposed layer that is spaced from the surface of the chamber wall.

The desired segregation of the snow and vapor is accomplished by the time the discharge reaches the open front of each one of the chambers l5. The snow layer for each chamber will be arranged adjacent the inner side wall l'l whil the vapor layer will be arranged outwardly of the snow layer, or adjacent th discharge pipe l3. The final discharge stream, therefore, will be formed by the segregated discharges from the two parallel chambers. The snow layers from the two chambers will lie adjacent to each other and immediately will merge. The vapor layers of the two discharges will be located outwardly of the snow layers and will sandwich the snow layers therebetween. It will be appreciated, therefore, that the final discharge will consist of a core that is formed by the two merged snow layers with the vapor layers shielding the snow core from the surrounding atmosphere. This final discharge stream will have a width which corresponds With the length of each chamber while the depth or thickness of the final stream will be approximately equal to the distance between the adjacent sides of the discharge pipes The carbon dioxide discharge obtained by means of this apparatus has been found to be extremely effective in combatting outdoor fires that are burning in the presence of high velocity natural winds. It will be appreciated that the field of application, or area of coverage, of the stream is very large and the concentration of the dense snow in the core of the stream and the shielding of this snow from the surrounding atmosphere by the outer vapor layers makes it possible to project the stream a considerable distance while maintaining an entirely effective extinguishing concentration.

The foam generating and discharging portion 7 of the fire extinguishing apparatus is illustrated in Figs. 2 and 3 as including four .guns If) that are all connected at their inner ends to the manifold 22!. The foam producing materials are supplied to this manifold by the supply pipe 22 which leads to a suitable source of supply. The foam generating and discharging guns that are specifically disclosed are of the type that produce mechanical-air foam; i. e., foam that is produced by causing a solution of water and a foam stabilizer to entrain or entrap air, or other suitable gases, to form the foam bubbles. It is to be understood, however, that foam generating and discharging guns of the type that will handle chemical foams, produced from a mixture of two solutions or from water to which dry powder chemicals are added, may be substituted for the type of foam gun illustrated. Foam stabilizers and foam producing solutions and dry powders are well known in the art and are fullydisclosed in the aforementioned copending application filed in the name of Charles A. Getz, Serial No. 551,869.

Each one of these guns IE is disclosed in Fig. 4 as including a gun body 23 which is suitably connected to the manifold 2!. This body is hollow and has its outer or front Wall 24 formed with r a suitable number of threaded openings 25 to receive the orifice tips 26. The mechanical-air foam producing solution is discharged from the body 23 through these tips so that it will traverse the air aspirating cage 2?, The solution will entrain and entrap air from the surrounding atmosphere while passing through this cage. The resultant mixture will flow into the foam ejector tube 23. as a solid stream from the outer end 28a of the tube.

Fig. 2 discloses the four foam guns if] as diverging with respect to each other and relative to the length of the carbon dioxide discharge nozzle structure 8. These diverging guns pass through four openings formed in the inner curved wall it of the lower chamber 5. The tubes 28 of these guns are insulated, by mean of the rings 29, where they pass through the wall of the carbon dioxide discharge chamber it to prevent the low temperature of this chamber wall from affecting the temperature of the foam flowing through the ejector tubes 28 of the foam guns.

The description given above of the carbon dioxide discharge nozzle 9 clearly points out the peculiar characteristics of this nozzle which result in the production of a carbon dioxide discharge that possesses highly effective range and penetrating characteristics as well as a large field of application, or area of coverage. It will be appreciated that the foam should be discharged into the carbon dioxide discharge in such a manner that the foam will be uniformly distributed throughout the width of the carbon dioxide stream and so that the foam will not materially lessen the effectiveness or desirable characteristics of the carbon dioxide discharge. This desired result can be obtained with the carbon dioxide discharge nozzle Q and the foam generating and discharging guns ii) arranged in the manner illustrated in Fig. 4. It will be noted that the foam guns discharge the foam into the snow core of the carbon dioxide stream because of the angular relation that exists between the foam guns and the carbon dioxide nozzle. The divergent arrangement of the foam guns produces a uniform distribution of the foam throughout the width of the carbon dioxide discharge stream.

Figs. '5 and -6 diagrammatically illustrate one The generated foam will be discharged type of composite carbon dioxide and foam dis: charge that can be produced by the method and apparatus embodying this invention; These figures also illustrate the fire extinguishing area and foam bianket coverage that results from the direct application of the extinguishing materials to the fire zone when the carbon dioxide nozzle and foam guns are arranged as illustrated. The dash lines A in Figs. 5 and 6 designate the margins of the carbon dioxide discharge. The dotted lines B of Fig. 5 designate the four solid streams of foam that are discharged into the carbon diOX-. ide stream. The area of direct applicationof the carbon dioxide and foam to ahorizontal surface C is represented by the character D in Fig. 5.

In this area of direct application D, the composite discharge of carbon dioxide and foam will effect substantially simultaneous extinguishment of the fire and application of a reignition preventing foam blanket. Without intending to limit the invention to any such specific application or example, it will be pointed out that ground coverage areas D measuring approximately ten feet in width and from thirty to forty feet in length can be obtained with discharge apparatus conforming to the following specifications:

The discharge apparatus is located approximately three feet above the ground surface C. The carbon dioxide discharge nozzle 9 is inclined 23 toward the ground while the foam guns I [I are inclined 3 way from the ground level.

The carbon dioxide discharge nozzle 9 measures approximately seven feet in length and approximately eight inches in depth. Carbon dioxide at the rate of twelve hundred pounds per minute is discharged from the nozzle 9. The four foam guns have a total discharge capacity of approximately one hundred gallons of foam solution per minute.

The liquid carbon dioxide should be maintained at its source under a vapor pressure of at least three hundred pounds per square inch. The foam solution should be delivered to the foam guns under a pressure of from ninety pounds to a hundred and twenty pounds per square inch.

It will be appreciated that by placing separate control valves in the carbon dioxide supply pipe l2 and in the foam solution supply pipe 22, the ratio of the foam discharge to the carbon dioxide discharge can be varied as desired. In fact, occasions will arise when it is desirable to stop the simultaneous discharge of carbon dioxide and foam and continue to discharge foam all by itself. For example, afterafire is completely extinguished by the combined discharge of carbon dioxide and foam, it may be desirable to build up a thicker foam blanket over the coverage area. This can be accomplished by discontinuing th discharge of carbon dioxide while the foam guns remain in operation. Also, it may be desirable under certain conditions to first effect extinguishment of a fire by discharging carbon dioxide only and then to produce a reignition preventing foam blanket by following up the carbon dioxide discharge with a foam discharge from the several foam guns. These various types of application of the extinguishing materials readily may be obtained by proper manipulation of valves in the supply pipes l2 and 22.

It is to be understood that the form of this invention herewith shown and described is to be taken as a preferred example of the same, and that various changes in practicing the hereindescribed method, and in the shape, size, and arrangement .of parts of the apparatus that is shown producing a carbon dioxide discharge stream of.

substantially greater width than thickness in cross section'and having an effective range wh ch is several times greater than said width, generating foam, discharging the foam into the carbon dioxide stream in such a manner that the foam will be distributed throughout the width of said stream and its range will correspond with that of the carbon dioxide stream, and directing the composite carbon dioxide and foam discharge with reference to the fire zone so that the area of direct application of the extinguisher will substantially correspond with the width and range of the stream whereby the combined action of the carbon dioxide and foam will effect substantially simultaneous extinguishrnent of the fire and application of a reignition preventing foam blanket over said area of direct application.

2. A method of quickly extinguishing a fire and preventing reignition of the combustible material for a considerable period of time after application of the extinguisher has ceased, comprising producing a carbon dioxide discharge stream of substantially greater width than thickness in cross section and having an effective range which is several times greater than said width, generating foam, discharging a plurality of spaced solid streams of the foam into the carbon dioxide stream with the foam streams diverging with respect to each other relative to the width of and extending at a slight angle relative to the thickness of the carbon dioxide stream so that the foam will be distributed throughout the width of said carbon dioxide stream and its range will correspond with that of the latter stream, and directing the composite carbon dioxide and foam discharge with reference to the fire zone so that the area of direct application of the extinguisher will substantially correspond with the width and range of the stream whereby the combined action of the carbon dioxid and foam will effect substantially simultaneous extinguishment of the fire and application of a reignition preventing foam blanket over said area of direct application.

3. A method of quickly extinguishing a fire and preventing reignition of the combustible material for a substantial period of time after application of the extinguisher has ceased, comprising conducting liquid carbon dioxide to a relatively long region of release, releasing the liquid through a plurality of constricted orifices arranged along said region to permit sudden expansion of the liquid to effect its conversion into snow and vapor, maintaining the flowing snow and vapor in confinement until the separate discharges merge along the length of said region, discharging said merged snow and vapor to the atmosphere so as to produce a stream having a width at least equal to the length of said region and an effective range which is several times greater than said width, generating foam, discharging the foam into the carbon dioxide snow and vapor stream in such a manner that the foam will be distributed throughout the width of said stream and its range will correspond with that of the carbon dioxide stream, and directing the compositecarbon di oxide and foam discharge on to the fire so as toeffect extinguishment of the fire and the application of a 'reignition preventing foam blanket over the area of application of the extinguisher.

4. A method of quickly extinguishing a fire and,

preventing reignition of the combustible material for a considerable period of time after application of the extinguisher has ceased, comprising conducting liquid carbon dioxide to a relatively long region of release, releasing the liquid, through a,

plurality of constricted orifices arranged along said region to permit sudden expansion of theliquid to effect its conversion into snow and vapor, maintaining the flowing snow and vapor,

least equal to the length of said region and an:

effective range which is several times greater than said width, generating foam, discharging a plurality of spaced solid streams of the foam into the carbon dioxide snow and vapor stream with the foam streams diverging with respect to each other relative to the width of and extending at a slight angle relative to the thickness of the carbon dioxide stream so that the foam will be distributed throughout the width of said carbon dioxide stream and its range will correspond with that of the latter stream, and directing the composite carbon dioxide and foam discharge with reference to the fire zone so that the area of direct application of the extinguisher will substantially correspond with the width and range of the carbon dioxide stream whereby the combined action of the carbon dioxide and foam will effect substantially simultaneous extinguishment of the fire and application of a reignition preventing foam blanket over said area of direct application,

5. A method of quickly extinguishing a fire and preventing reignition of the combustible material for a considerable period of time after application of the extinguisher has ceased, comprising effecting sudden release of liquid carbon dioxide to lower its pressure sufliciently to form snow and vapor, flowing said snow and vapor along a curvilinear path arranged to terminate in an elongated discharge zone to effect segregation of these components, forming the segregated snow and vapor components into a stream discharging to the atmosphere from the entire length of the elongated discharge zone so as to have a width at least equal to said length and having an effective range which is several times reater than said width, generating foam, distributing the foam into the carbon dioxide stream in such a manner that the foam will be distributed throughout the width of said carbon dioxide stream and its range will correspond with that of the latter stream, and directing the composite carbon dioxide and foam discharge with reference to the fire zone so that the area of direct application of the extinguisher will substantially correspond with the width and range of the carbon dioxide stream whereby the combined action of the carbon dioxide and foam will efiectsubstantially simultaneous extinguishment of the fire and application of a reignition preventing foam blanket over said area of direct application.

6. Fire extinguishing apparatus for producing a composite discharge of carbon dioxide and foam, comprising an elongated chambered structure open on one side throughout its length,

aim-gees means" for releasing liquid carbon dioxide: into said" chambered structure to ge mit it to expand to form snow and vapor for L; go through said side opening to form a str or elongated cross section, means for genera foam, and mean for discharging the foam (.60 the carbon dioxide snow and vapor stream so that the foam will be distributed throu'gigfi-ut the stream in the direction of its major cross sectional dimension.

7. Fire extinguishing apparatus for producing a composite discharge of carbon dioxide and foam, comprising an elongated chambered structure open on one side throughout its length, means for releasing liquid carbon dioxide into said chambered structure to permit it to expand to form snow and Vapor for discharge through said Side opening to form a stream of elongated cross section, means for generating foam, and means for discharging a plurality of spaced solid streams of the foam into the carbon dioxide diverging with respect to each other in the direction of the major cross sectional dimension of the carbon dioxide stream so that the foam will be uniformly distributed throughout said latter stream. .1 I

8. Fire exting'iu'shing apparatus for producing a composite discharge of carbon dioxide and foam, comprising an elongated chambered structure open onone side throughout its length, means for releasing liquid carbon dioxide into said chambered structure to permit it to expand to form snow and vapor for discharge through said side opening to form a stream of elongated cross section, and a plurality of foam generating and dischargin devices extending through said chambered. structure and its open side to discharge their foam into the snow and vapor stream.

I-IILDING V. WILLIAMSON. 

